Conventionally, exchange of calls and electronic mails using a phone and a personal computer or the like has facilitated and enlarged communication between family members, or friends. By using communication tools such as a phone and an electronic mail, a user can contact his or her friend or family easily and conveniently even when they are far away from the user.
Further, with recent trend in which phone charges are significantly reduced and increasing number of people own a portable phone terminal or Personal Digital Assistant (PDA) exclusively for themselves, communication using such a portable device has become handy and increasingly important. Under the circumstances, many users exchange an electronic mail even with their friends who are not in familiar terms with the users. Consequently, more communication partners are registered in an address book of such a communication apparatus than a hand-written address book. Moreover, since data registered in the address book is managed in the order of partner names, a partner with whom a user has not contacted for a long time and a partner with whom the user contacts frequently are not sorted out, which makes it hard to find instantly the contact address of a partner whom the user wishes to contact.
In this regard, Patent Document 1 describes a technique that communication partners in an address book are listed in the order of communication frequency, while Patent Document 2 describes a technique that a communication partner whom a user has not contacted for a long time is deleted from an address book. By using those techniques, it is possible to select a communication partner whom the user contacts frequently, thereby improving operability of an apparatus.    Patent Document 1: Japanese Patent Application Publication No. 2003-198708    Patent Document 2: Japanese Patent Application Publication No. 2004-357142
However, though the technique described in Patent Document 1 facilitates a call to a communication partner with a high frequency, that technique does not make a user aware of a communication partner whom the user does not intend to, but forgets to call. On the other hand, Patent Document 2 describes displaying a list of communication partners whom a user has not contacted for a long time when allowing deletion of registered data, which makes the user aware of a communication partner whom the user forgets to contact by confirming the displayed list. However, even though the user finds his or her important communication partner by confirming one by one deletion candidates registered in the address book, it is cumbersome for the user to search the contact address of the important partner from a large amount of data registered in the address book to contact the partner according to the contact address. Consequently, the user may postpone searching the address and eventually may forget to contact the partner. If the user postpones contacting a partner as it is cumbersome, the user may be estranged from the partner, which is contrary to increasing importance of communication by using the communication apparatus.
In view of the above circumstances, it is an object of the present invention to provide a communication apparatus that is capable of avoiding situation in which a user is estranged from a communication partner, a communication program storage medium, and a communication method thereof.